Delicious is a pretty good place to look for bookmarked data sets.

http://delicious.com/sidmitra/datasets

Also,

A lot of conversation around data sets happens on Google groups such as "Get the info"

http://groups.google.com/group/get-theinfo

Also, http://delicious.com/popular/datasets

I've been collecting a few myself

http://datavis.slinkset.com/

There's also www.reddit.com/r/opendata

Great resource. I've already found some stuff I've been looking for for a while.

I like how the top link right now [1] is nicely meta.

[1] http://www.reddit.com/r/datasets/.xml